Yellowstone National Park
Three endemic species in Yellowstone
Ross's bentgrass
Yellowstone sand verbena
Yellowstone sulfur wild buckwheat
Ross’s bentgrass grows only in the geyser basins in the Firehole River drainage and at Shoshone Geyser Basin. Thermal habitats are distinguished primarily by their elevated soil temperatures, and heat stress is the primary factor controlling the distribution of plants within them. This species seems to require locations providing the right combination of moisture and warmth that create a natural greenhouse. As a result, this grass is one of the first plants to green up in warm pockets of geyserite—sometimes as early as January.
Yellowstone sand verbena Yellowstone sand verbena (Abronia ammophila) occurs along the shore of Yellowstone Lake. Taxonomists debate the relationship of this population of sand verbena to other sand verbenas. It may be distinct at the subspecific level, and is certainly reproductively isolated from the closest sand verbena populations in the Bighorn Basin of Wyoming east of the park. The presence of a sand verbena at 7,700 feet elevation in the northern Rockies is unexpected, as most members of this North American genus occur in the Southwest or along the Pacific Coast. One speculation by botanists is that the warmth provided by the geothermal activity in the area enabled a genus which had evolved in a warmer climate to gradually adapt to conditions in Yellowstone. Today, Yellowstone sand verbena tolerates the long, cold winters and uses the brief summer to bloom and reproduce.
Yellowstone sulfur buckwheat is adapted to survive on barren, slightly geothermally influenced open areas. It apparently does not tolerate any shading, so it is a conspicuous component of relatively dry plant communities adjacent to the park’s thermal areas. The geographic range of this variety is highly restricted, having been found only from the Upper, Midway, and Lower geyser basins to the vicinity of Madison Junction. Adaptation to life in a geothermal setting means that this taxon has to be able to move with changes in the geothermal system. Yellowstone sulfur buckwheat is capable of recolonizing disturbed areas, as demonstrated by its presence near the Old Faithful Inn and Visitor Education Center, and other locations in the Upper Geyser Basin.